<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #s1 {
            width: 100px;
            height: 100px;
        }

        #s2 {
            border: 2px solid #666;
        }

        #d1 {
            width: 100px;
            height: 100px;
            margin:20px;
            padding:5px;
            border:2px solid #000;
            float: left;
            background-color: red;
            box-sizing: border-box;
        }

        #d2 {
            width: 100px;
            height: 100px;
            float: right;
            background-color: blue;
        }

        .fixclear::after
        {
            content:' ';
            height:0;
            display:block;
            clear:both;
        }
    </style>
</head>

<body>

    <span id="s1">1111</span>
    <span id="s2">2222</span>
    <div class="fixclear">
        <div id="d1">33333</div>
        <div id="d2">44444</div>
        
    </div>
    这个是下面文字
</body>

</html>